People travelling to the UK face a fine of up to £1,000 if they do not quarantine for 14 days. Passengers arriving at London Stansted Airport explain how their plans have been affected.
'We have a lot of freedom in Germany right now'
On the first day of quarantine, Anna Wulf and Albert Mackintosh have made an international move because she has a new job.
The quarantine rules mean the couple have had to leave behind a lot of their belongings in Berlin and move sooner to give them time to self-isolate before Ms Wulf starts her job at King's College London.
"We have a lot of freedom in Germany right now and coming to a country that is a lot more restricted than we've ever been, it's weird," said Ms Wulf, 26.
Mr Mackintosh, 28, said moving house, while also figuring out the logistics of how to quarantine without being allowed out for basic necessities such as food, had been "very stressful".
They have had to rely on his family to make sure they can follow the restrictions at their new London home.
He said: "My dad is dropping off a car here from Norfolk. He and my brother have come down in two different cars and left one here, which we'll pick up and drive to London to our apartment, and they've put food in the car."
'Quarantine is like a staycation'
Students Yuliyan Stoyanov, 20 and Bozhana Nikolova, 21, left the UK in March when the country entered lockdown, "leaving everything behind".
They have returned from Bulgaria to sort out their accommodation and pack up their belongings.
"We bought the tickets before we realised there was going to be quarantine but it didn't change much because we're coming here to pick our stuff up, so it doesn't really matter," Ms Nikolova said.
The second-year University of Sheffield students will be packing up their flats but have yet to organise a return to Bulgaria because their return flights have been cancelled.
Mr Stoyanov said he planned to treat quarantine like a "staycation".
"I'm just sitting at home, luxuriating and having fun."
At the scene: Phil Shepka, BBC News
To say being at an international airport during a global pandemic is a surreal experience would be an understatement.
Instead of people milling around in departures in eager anticipation of their flight, or waiting for their loved ones to come through the arrivals gate, the main concourse is eerily quiet.
Signs remind people to keep 2m apart from each other, but social distancing within the terminal of Stansted Airport should not be a problem - there are only about 150 people milling around the normally bustling airport.
The majority of those have donned face coverings, and gloves are being worn by some. Only one shop remains open for food, and the airport's prayer room has been closed.
'I can order food online'
IT developer Uche Ishionwu, 43, was visiting his children in Germany and had originally wanted to get a flight home before the quarantine was in place but found they were all very expensive.
However, he said he had no regrets about waiting for a cheaper flight because self-isolating would not much alter his "new normal" at home in East Croydon, south London.
"I decided I'll be working from home anyway so I might as well come back and risk being quarantined... I did second guess it but realised that there wouldn't be any difference anyway because you can order [food] online."
'Just common sense'
Student Ronja Ritter has come back to the UK from Germany to find a new place to live when her current tenancy ends.
With the contract up in three weeks, Ms Ritter, who studies at the University of Essex in Southend, needed to return to the UK but said she was not bothered about having to self-isolate.
She said: "It didn't impact my decision to come. Isolating is fine. When I went from the UK to Germany when the virus started, I did it myself, so I isolated for two weeks even though there was no real need. It was just common sense."
Filling her time would not be an issue, she said. Organising a move and doing some reading would keep her more than busy.